JP2001015312A - Manufacture of magnetic electromagnetic wave absorbing paste, the magnetic electromagnetic wave absorbing paste, electronic component and printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain magnetic electromagnetic wave absorbing paste, having high absorption coefficient at high frequency and over a wide band. SOLUTION: FeO 11, MnO 12, ZnO 13 and a binder 10 are mixed, thereby forming a mixed solution 14 (a). The mixed solution 14 is spread on a base film 16, which is drawn out by a roll 15a and wound up by a roll 15b (b). The mixed solution 14 dropped on the base film 16 is subjected to coating of at most 2 μm thickness. After coating, the mixed solution 14 is heated and dried. From above the base film 16, a flat ferrite 17 which is turned into a sheet type is peeled, thereby formation of the flat ferrite 17 is finished (c). The formed flat ferrite 17 is ground and baked at 900-1,250 deg.C, thereby obtaining ferrite powder. The ferrite powder is mixed with a material for paste, and a magnetic electromagnetic absorbing paste is made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic electromagnetic wave absorbing paste, a method of manufacturing the same, and an electronic component and a printed board, and more particularly to a magnetic electromagnetic wave absorbing paste used for small electronic equipment, a method of manufacturing the same, and an electronic component and a printed board.

[0002]

2. Description of the Related Art Since electronic devices have been miniaturized and high frequencies have been used, there is a strong demand for reducing interference between components due to electromagnetic waves.

[0003] Generally, Mn-Zn (manganese-zinc) ferrite has effective electromagnetic absorption characteristics. When these Mn-Zn ferrites are powdered and used as a magnetic electromagnetic wave absorbing paste to obtain broadband and high magnetic loss characteristics, the effect depends on the shape and composition of the powder. Generally, in order to obtain high frequency and broadband characteristics,
The effect is great if the ferrite particles are flattened and combined with a resin. In particular, as in the case of a flat shape, a higher effect is obtained when the aspect ratio of the particles is larger.

[0004]

However, in general, ferrite cannot be rolled and is used as a granular powder, and it has been difficult to broaden the band.

On the other hand, Fe-Si, Fe-A
A magnetic electromagnetic wave absorbing paste using scale-like powder obtained by rolling a metal such as l-Si is used. However, when a metal is used as a powder, the amount of reflection of electromagnetic waves is larger than that of ferrite, and the electromagnetic wave absorption characteristics are inferior. Therefore, it has been difficult to obtain a magnetic electromagnetic wave absorbing paste having high absorption characteristics over a wide band. In particular, it was difficult to obtain a thin layer (2 μm or less) magnetic electromagnetic wave absorbing paste.

The present invention has been made in view of the above points, and has as its object to provide a magnetic electromagnetic wave absorbing paste having a high absorptance in a high frequency band. Another object of the present invention is to provide a method for producing a magnetic electromagnetic wave absorbing paste having high absorption in a high frequency band and a wide band.

Still another object of the present invention is to provide an electronic component coated with a magnetic electromagnetic wave absorbing paste having high absorption in a high frequency band and a wide band. Another object of the present invention is to provide a printed board coated with a magnetic electromagnetic wave absorbing paste having high absorption in a high frequency and a wide band.

[0008]

In order to solve the above-mentioned problems, the present invention provides a method for producing a magnetic electromagnetic wave absorbing paste, which comprises coating a film with a mixture of fine powder ferrite and a binder to form a ferrite sheet. Forming, peeling off the ferrite sheet from the film, pulverizing the ferrite sheet and then firing to obtain a ferrite powder, mixing the ferrite powder with a paste material, and producing a magnetic electromagnetic wave absorbing paste A method for producing an electromagnetic wave absorbing paste is provided.

Since ferrite cannot be rolled, it is coated once on a film, dried, peeled off in a sheet form, crushed and fired to produce a ferrite powder having an aspect ratio of 10 or more. To produce a magnetic electromagnetic wave absorbing paste.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for producing a magnetic electromagnetic wave absorbing paste and a magnetic electromagnetic wave absorbing paste according to the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 are views showing the steps of the method for producing a magnetic electromagnetic wave absorbing paste of the present invention. FeO (iron oxide) 1 as a raw material for producing flat ferrite
1, MnO (manganese oxide) 12, and ZnO (zinc oxide) 13 are used, and a binder 10 is used as a matching resin.

Next, FeO11, MnO12, Zn
O13 and the binder 10 are mixed. At this time, the binder 10 uses nitrocellulose as a binder and carbitol acetate as a diluent. Thereby, the mixed liquid 14 is generated (a).

Next, the mixed liquid 14 is applied onto the base film 16 which is pulled out by the roll 15a and wound up by the roll 15b (b). A roll 15c is provided between the roll 15a and the roll 15b, and the mixed liquid 14 applied on the base film 16 is separated by the roll 15c.
Press down to coat to a thickness of 2 μm or less. The mixed solution 14 coated on the base film 16 is heated at 70 ° C. or less and dried. After drying, the sheet-shaped flat ferrite 17 is peeled off from the base film 16. Thereby, the formation of the flat ferrite 17 is completed (c).

As shown in FIG. 2, the flat ferrite 17 produced in FIG.
17n is generated. The ferrite pieces 17a to 17n have various shapes, a thickness of 2 μm or less, and a short side length of about 40 to 50 μm (a).

Next, the ferrite pieces 17a to 17n are fired at about 900 to 1250 degrees. Here, although the ferrite pieces 17a to 17n have a thickness of 2 μm or less, the thickness shrinks to 1.5 μm or less by firing at about 900 ° to 1250 °. Thereby, flat ferrite powder 18 is generated.

Next, the flat ferrite powder 18, the diluent 19, and the binder 20 are mixed. As the diluent 19, an organic solvent is used, and as the binder 20, an epoxy resin is used. Here, the flat ferrite powder 18
Is made to be 60% or more. Further, the amount of the diluent 19 is determined so that the viscosity becomes 100 to 1000 poise. Thereby, the ferrite paste 21 is generated (b).

The ferrite paste is a paste in which ferrite which absorbs electromagnetic waves is included in the paste, and is a magnetic electromagnetic wave absorbing paste. Next, the electronic component to which the ferrite paste is applied will be described.

FIG. 3 is a structural view showing an IC to which a ferrite paste is applied. The ferrite paste 21
It is applied so as to enclose the IC 22. Thereby, the ferrite paste 21 absorbs the electromagnetic wave generated from the IC 22. Suppress the effect of electromagnetic waves on other electromagnetic components,
Reduce the effects of electromagnetic waves from other electronic components.

Next, a case where a ferrite paste is applied to an IC mounted on a substrate will be described. FIG. 4 is a diagram in which a ferrite paste is applied to the mounted IC.

By applying the ferrite paste 21 after mounting the IC 24 on the substrate 23, the effect of electromagnetic waves on other substrates is suppressed, and the effect of electromagnetic waves from other substrates is further reduced.

In the above description, an IC has been described as an example of an electronic component to which a ferrite paste is applied. However, the present invention is not limited to this, and other electronic components can also be applied with a ferrite paste. .

[0022]

As described above, once coated on a film, dried and then peeled off into a sheet, crushed and fired to produce a ferrite powder, which is mixed with a paste material to form a magnetic electromagnetic wave. Since the absorption paste is manufactured, a magnetic electromagnetic wave absorption paste having ferrite particles having an aspect ratio of 10 or more can be manufactured, and a magnetic electromagnetic wave absorption paste capable of absorbing broadband, high frequency electromagnetic waves with a high absorption rate can be manufactured. it can.

Further, the magnetic electromagnetic wave absorbing paste of the present invention is a magnetic electromagnetic wave absorbing paste mainly composed of ferrite particles having an aspect ratio of 10 or more, so that it is possible to absorb broadband and high frequency electromagnetic waves at a high absorption rate.

Further, in the electronic component of the present invention, since the magnetic electromagnetic wave absorbing paste mainly containing ferrite particles having an aspect ratio of 10 or more is applied, high-frequency and high-band electromagnetic waves emitted from the electronic component can be sufficiently removed. Can be reduced.

Furthermore, in the printed board of the present invention, the electronic component is mounted on a printed board, and the electronic component is coated with a magnetic electromagnetic wave absorbing paste mainly composed of ferrite particles having an aspect ratio of 10 or more. The interference of the above high frequency and wide band electromagnetic waves can be sufficiently reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a method for producing flat ferrite necessary for a method for producing a magnetic electromagnetic absorbing paste of the present invention.

FIG. 2 is a view illustrating a method for producing a magnetic electromagnetic absorbing paste using the flat ferrite of the present invention.

FIG. 3 is an IC coated with the ferrite paste of the present invention.
FIG.

FIG. 4 is a diagram in which a ferrite paste is applied to the mounted IC of the present invention.

[Explanation of symbols]

10 binder, 11 FeO, 12 MnO, 13
... ZnO, 14 ... mixture, 15a ~ 15c ... roll, 1
6 ... base film, 17 ... flat ferrite, 17a-
17n: ferrite piece, 18: flat ferrite powder, 1
9 diluent, 20 binder, 21 ferrite paste, 22 IC, 23 substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E040 AB03 CA13 HB03 HB14 HB17 NN02 NN18 5E041 AB02 BB03 CA10 HB03 HB17 NN02 NN18 5E321 AA21 BB32 BB33 CC30 GG11

Claims (6)

[Claims] 1. A method for producing a magnetic electromagnetic wave absorbing paste, comprising: mixing a mixture of fine powder ferrite and a binder;
A ferrite sheet is formed by coating the film, the ferrite sheet is peeled off from the film, the ferrite sheet is crushed and baked to obtain a ferrite powder, and the ferrite powder is mixed with a paste material. A method for producing a magnetic electromagnetic wave absorbing paste, which comprises producing the paste. 2. The method for producing a magnetic electromagnetic wave absorbing paste according to claim 1, wherein said ferrite sheet has a thickness of 2 μm or less. 3. The firing temperature is 900 degrees or more and 125 degrees.
The method for producing a magnetic electromagnetic wave absorbing paste according to claim 1, wherein the temperature is set to 0 ° C or lower. 4. A magnetic electromagnetic wave absorbing paste comprising a ferrite particle having an aspect ratio of 10 or more as a main component. 5. An electronic component, wherein a magnetic electromagnetic wave absorbing paste mainly containing ferrite particles having an aspect ratio of 10 or more is applied. 6. A printed circuit board on which electronic components are mounted, wherein the electronic components are mounted on a printed circuit board, and a magnetic electromagnetic wave absorbing paste mainly containing ferrite particles having an aspect ratio of 10 or more is applied to the electronic components. A printed board characterized by the following.